This invention relates to apparatus for improving the safety of a stove and, in particular, the safety of a wood burning stove that is capable of producing creosote.
Creosote is a highly combustible material that is driven out of wood or wood products during the burning process in the form of a gas. When the burning efficiency of the stove is low, the creosote does not ignite and passes through the flue into the vent chamber of the chimney. As the relatively hot gases pass over the cooler chimney surfaces, the creosote condenses on the chimney walls. After a period of time, the creosote coating will build up to a level that can affect the chimney draw and present a fire hazard. If left unchecked, this highly combustible material will ignite producing extremely intense heat capable of cracking the chimney and spreading to surrounding structures thereby endangering both life and property.
The safest method of preventing chimney fires is to visually inspect the inside of the chimney on a regular basis and clean the chimney when the creosote build-up reaches about one quarter inch in depth. Typically, visual inspection of the chimney heretofore required that the stove be shut down and access be gained to the lower part of the chimney either through the flue opening or an access door. This type of inspection thus oftentimes is not only time consuming but inconvenient as well so that many stove users either ignor the inspection or put it off for dangerously long periods of time.
As will be explained in greater detail below, the apparatus of the present invention provides visual access to the interior of a working chimney while the stove is in operation. Accordingly, the build-up of creosote on the chimney walls can be continually monitored as well as the condition of the smoke passing through the chimney. A great deal about the burning efficiency of the stove can be learnd by observing the color and density of the smoke along with the smoke patterns. This information can be used to determine optimum stove settings which lead to a more efficient and complete burning of the fuel. This decreases the rate at which creosote builds up on the chimney wall, extends the interval between cleanings and considerably reduces the risk of fire.
By monitoring the smoke patterns moving up the chimney, minute openings or cracks in the chimney wall can be quickly identified and repaired before they become a major hazard. The smoke stream line normally moves up the chimney in quiet laminar flow patterns. Any disturbance in this pattern is a clear indication that outside air is being drawn into the chimney through a crack or the like. The flow disturbance manifests itself in the form of small eddys located adjacent to the crack. Accordingly, the break can be accurately pinpointed and repairs quickly carried out before further thermal damage is done to the chimney.
In U.S. Pat. No. 2,355,466 ther is described a flue pipe having a hole formed therein through which the fire pot of a hot water heater is observed. The purpose of the hole is to permit inspection of the burner and the condition of the flame. A door or cover is removably placed over the hole in the pipe in an effort to contain the flue gases and to preserve the airtight integrity of the flue system. The door, however, is not sealed and it is doubtful that this type of observation would be suitable for use in a wood burning environment that gives off relatively dense smoke.